1. The Field of the Invention
The present invention relates to systems and methods for restoring data that has been lost. More particularly, embodiments of the invention relate to systems and methods for restoring data in a database mirroring environment.
2. Related Technology
Computer networks are ubiquitous in both residential and commercial environments. In addition to widespread Internet use, local area networks (LANs) allow users to share computer services. Many corporate entities use LANs within their organizations and provide consumers with access to data over the Internet.
Dependence on computers and computer networks has created a need for improved availability and reliability of data. Many commercial entities store nearly all business data on a computer network, and network users expect uninterrupted access to the data at any given time. Software and hardware with enhanced capabilities are needed to support this demand for uninterrupted access to data. As the amount of data stored on a network, and the demand for accessibility to data on the network, grows, it becomes increasingly difficult to protect data from unforeseen events such as system failures, file corruption and viruses.
Protecting data from potentially devastating events is typically accomplished through a combination of software to back up the data, and secure hardware to store the backed-up data. As the amount of data to be preserved increases, the process of backing up the data becomes more complex. For example, gigabytes of data cannot be quickly transferred from a primary location to a backup location. In addition, making the data unavailable while the backup is performed is not a feasible option for environments where continual access to data is imperative.
Although backing up large amounts of data is problematic, it is not the only problem related to typical data backup systems. Network users and administrators may wish to back up various kinds of data. In addition to backing up files, network users may also wish to back up applications and services. Backing up applications and services can be challenging. For example, applications and services often have open files when the backup is initiated but because open files cannot generally be effectively or reliably backed up, such files are often skipped during backup operations. As a result, additional backup applications are often needed to help manage backup operations for applications and services whose files were skipped during the initial file system backup.
Another problem related to backing up data concerns the manner in which the backed-up data will be tracked when the data is moved to a backup location. In particular, when data is backed up, the backup copy is moved to a new location, thus making it necessary to have a record of how the data has been stored in order to facilitate access to the stored data. Typically, backup systems include a database that records the exact location of each file or application that is backed up. When a user wishes to locate or retrieve a file from the backup system, the database locates the file at the stored location of the file in the backup media.
While tracking the location of the backed-up data, typical backup software systems simply place the data in a backup location and track the location in an index. More intelligent database software systems have the ability to sort the data as it is backed up, so that the data is stored intelligently. For example, a more sophisticated database software system can store backups of like files on the same media. Sorting and storing data in this manner allows for more efficient data storage and retrieval.
Another shortcoming of typical backup software systems is their inability to allow for relocation of the data within a network, or to have more than one copy of the data available within the network Although the backup software system collects data from all users on the network, the data itself is viewed as residing at one single location on the network and is not cross referenced to other locations. While the data on the network is backed up, this redundancy and cross referencing are not addressed.
Access to backed-up data is an important consideration in the configuration of database backup systems. A purpose of backing up data is to preserve data in a way so that if files are damaged or lost, the backup copy can be retrieved and the file can be restored. When a file is corrupted or lost, a user requests a backup copy of the file from the backup server. The backup server then locates the file, using the location stored in the file index and media database, retrieves the file, and makes the file available for the user.